% This file is part of the Stanford GraphBase (c) Stanford University 1993 @i boilerplate.w %<< legal stuff: PLEASE READ IT BEFORE MAKING ANY CHANGES! @i gb_types.w \def\title{QUEEN} @* Queen moves. This is a short demonstration of how to generate and traverse graphs with the Stanford GraphBase. It creates a graph with 12 vertices, representing the cells of a $3\times4$ rectangular board; two cells are considered adjacent if you can get from one to another by a queen move. Then it prints a description of the vertices and their neighbors, on the standard output file. An ASCII file called \.{queen.gb} is also produced. Other programs can obtain a copy of the queen graph by calling |restore_graph("queen.gb")|. You might find it interesting to compare the output of {\sc QUEEN} with the contents of \.{queen.gb}; the former is intended to be readable by human beings, the latter by computers. @p #include "gb_graph.h" /* we use the {\sc GB\_\,GRAPH} data structures */ #include "gb_basic.h" /* we test the basic graph operations */ #include "gb_save.h" /* and we save our results in ASCII format */ @# main() {@+Graph *g,*gg,*ggg; g=board(3L,4L,0L,0L,-1L,0L,0L); /* a graph with rook moves */ gg=board(3L,4L,0L,0L,-2L,0L,0L); /* a graph with bishop moves */ ggg=gunion(g,gg,0L,0L); /* a graph with queen moves */ save_graph(ggg,"queen.gb"); /* generate an ASCII file for |ggg| */ @; return 0; /* normal exit */ } @ @= if (ggg==NULL) printf("Something went wrong (panic code %ld)!\n",panic_code); else { register Vertex *v; /* current vertex being visited */ printf("Queen Moves on a 3x4 Board\n\n"); printf(" The graph whose official name is\n%s\n", ggg->id); printf(" has %ld vertices and %ld arcs:\n\n", ggg->n, ggg->m); for (v=ggg->vertices; vvertices+ggg->n; v++) { register Arc *a; /* current arc from |v| */ printf("%s\n", v->name); for (a=v->arcs; a; a=a->next) printf(" -> %s, length %ld\n", a->tip->name, a->len); } } @* Index.